Answer
The bricklayer works $3\;hours$
and the less experienced man works $4\; hours$.
Work Step by Step
Let the bricklayer works $x\;hours$.
And the less experienced man works $y\;hours$.
Total time is $=7\;hours$
$\Rightarrow x+y=7$ ...... (1)
Total number of bricks $=930$.
$\Rightarrow 150x+120y=930$ ...... (2)
Multiply equation (1) by $-4$.
$\Rightarrow -4x-4y=-28$ ...... (3)
Divide equation (2) by $30$.
$\Rightarrow 5x+4y=31$ ...... (4)
Add equation (3) and equation (4).
$\Rightarrow -4x-4y+5x+4y=-28+31$
Simplify.
$\Rightarrow x=3$
Substitute the value of $x$ into equation (1).
$\Rightarrow 3+y=7$
Isolate $y$.
$\Rightarrow y=7-3$
Simplify.
$\Rightarrow y=4$
Hence, the bricklayer works $3\;hours$ and the less experienced man works $4\; hours$.
