how to solve this delta math question

Question

On a snow day, Hunter created two snowmen in his backyard. Snowman A was built to a height of 35 inches and Snowman B was built to a height of 50 inches. The next day, the temperature increased and both snowmen began to melt. At sunrise, Snowman A's height decrease by 4 inches per hour and Snowman B's height decreased by 7 inches per hour. Let AA represent the height of Snowman A tt hours after sunrise and let BB represent the height of Snowman B tt hours after sunrise. Write an equation for each situation, in terms of t,t, and determine how tall each snowman is when they are the same height.

Answer 1

35 -4t = 50 - 7t

7t-4t = 50-35

3t = 15

t =15/3 = 5 hours when A and B are the same height = 15 inches