What is the decimal expansion of 13/8

Iam trying to solve a linear equation for the shoe size of someone 84" tall taking into consideration example 1 is 69" tall with a shoe size of 9 and example 2 is 72 inches tall with a shoe size of 11. i understand that the equation should be y=mx+b and that on the graph the answer is (3,2) but i just don't understand how to create the equation to solve for 84-inches and 60-inches tall questions. after two days, i need .

The graph of which equation includes the points (0, 10) and (10, 11)? y = 10x + 11 y = x + 10 y= 1/10x + 10 y = 1/10x + 11

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles