Please help I’m doing points

What is the length of the unknown leg in the right triangle ?

Kapil needed to buy a long wooden beam. he went to two sawmills that each charge an initial fee plus an additional fee for each meter of wood. the following equation gives the price (in dollars) of a wooden beam from the first sawmill as a function of its length (in meters). p = 5+20xp=5+20x

Reflect the point (7,0) across the y-axis