问计算两个字段的值

EN

<input name="ch3_training_days" type="text" value="0" maxlength="10" id="ch3_training_days" tabindex="8" title="Traning Days" class="DataFormTextBox" onblur="if(this.form.ch3_training_days.value>0) document.getElementById("ch3_training_days_benefit_total").focus();if(this.form.ch3_training_days.value<=0) document.getElementById("ch3_training_days_benefit_total").focus();"/>

<input name="ch3_training_days_benefit_total" type="text" maxlength="10" id="ch3_training_days_benefit_total" tabindex="168" title="Total" class="DataFormDropDownList" placeholder="Total" onfocus="if((this.form.ch3_training_days.value>0) && (this.form.ch3_training_days.value<=4)) ch3_training_days_benefit_total.value = Number(this.form.ch3_training_days.value*10); else if(this.form.ch3_training_days.value>4) ch3_training_days_benefit_total.value = '40'; else if((this.form.ch3_training_days.value<=0) || (this.form.ch3_training_days.value=='')) ch3_training_days_benefit_total.value = '0'; ch3_benefit_sub_total.value = ch3_training_days_benefit_total.value; document.getElementById('ch3_training_days_benefit_total').setAttribute('readonly', 'readonly');"/>


<textarea name="ch3_bsme" rows="2" cols="20" id="ch3_bsme" tabindex="13" title="Building Safety Month Event" class="DataFormTextBox" placeholder="Building Safety Month Event" onkeyup="TextLimit(this, 100)" onblur="TextLimit(this, 100)" onchange="var str = document.getElementById("ch3_bsme").value; var n = str.length; if(str.length<=0) document.getElementById("ch3_bsme_total").focus(); else if(str.length>0) document.getElementById("ch3_bsme_total").focus();">
</textarea>

<input name="ch3_bsme_total" type="text" maxlength="10" id="ch3_bsme_total" tabindex="15" title="Total" class="DataFormDropDownList" placeholder="Total" onfocus="var str = document.getElementById("ch3_bsme").value; var n = str.length; if(str.length<=0) ch3_bsme_total.value = '0'; else if(str.length>0) ch3_bsme_total.value = '10'; ch3_benefit_sub_total.value = ch3_bsme_total.value; document.getElementById('ch3_bsme_total').setAttribute('readonly', 'readonly');"/>


<input name="ch3_benefit_sub_total" type="text" value="0" maxlength="10" id="ch3_benefit_sub_total" tabindex="168" title="benefit sub-total" class="DataFormDropDownList" placeholder="benefit sub-total"/>