Then it is (8x-50)/3-10 = (10x+40)/5.
10X=520
X=52
A: The wall area to be painted in each room is 52㎡.
Analysis: The equation is based on "each first-class mechanic paints more walls 10㎡ a day than the second-class mechanic".
Namely: painting area of first-class mechanic-10= painting area of second-class mechanic.