Two mechanics worked on a car. The first mechanic worked for \( 5 \) hours and the second mechanic worked for \( 15 \) hours. The final bill for the work was \( \$ 1250 \) . What was the rate charged per hour by each mechanic if their combined rate (sum of the two rates) was \( \$ 140 \) per hour?
Real Tutor Solution
Quick Answer
let
rate for one car = x
rate for second car = y
so,
\(\left [ \begin{array} { c } { x + y = 140 } \\ { 5 x + 15 y = 1250 } \end{array} \right ] \)
Isolate \( x \) for \( x + y = 140 : \quad x = 140 - y\)
Substitute \( x = 140 - y \)
\( [ 5 ( 140 - y ) + 15 y = 1250 ] \)
Simplify
\( [ 700 + 10 y = 1250 ] \)
Isolate \( y \) for \( 700 + 10 y = 1250 : \quad y = 55\)
For \( x = 140 - y \)
Substitute \( y = 55 \)
\( x = 140 - 55\)
Simplify
\( x = 85\)
rate for one car = 85 per hour
rate for second car = 55 per hour
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