Abanana 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?

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