<human>:  Chang's Garden has two kinds of apples. Sweet ones and sour ones. He can sell the sweet ones for $.5 an apple. The sour ones sell for $.1 an apple. 75% of the apples he gets are sweet and the rest are sour. If he earns $40, how many apples did his trees give him?
<bot>: How many apples are sour? ** 25% of the apples are sour because 100 - 75 = <<100-75=25>>25
How much do the sweet apples sell for? ** The average price of an apple sold is $.4 because .75(.5) + .25(.1)= .4
How many apples did he get? ** He got 100 apples because 40 / .4 = <<40/.4=100>>100
#### 100