Aplumber charges an initial amount, x, to make a house call plus an hourly rate, y, for the time he is working. a 1-hour job costs $90 and a 3-hour job cost $210

answer

d. 10

explanation

the distance from point y to wx is the height of the triangle.

using pythagoras theorem,

group similar terms to get,

this implies that,

take positive square root of both sides to get,

this implies that,

2/3

step-by-step explanation: