A banana costs three times as much as an apple. The total cost of 1 banana and 1 apple is $1.60. If a represents the cost of 1 apple, which equation could you use to find a?

3a+a=1.60

We know that the cost of an apple and a banana equals $1.60

a + b = 1.60

We also know that the cost of a banana is 3 times that of an apple

3a = b

If we divide 4 from 1.60 we will get the price of 1 apple

4a = 1.60

1 apple costs $0.40

So that means 1 banana costs $1.20