Work is provided in the image attached.
We see here in the diagram that the base is a. We know this because the height is perpendicular to it. We also know the height is bsin(C) which, when replace h for bsin(C) and a for the base, we get A=absin(C), which is the second option.
Simplify
4ax+12-3ax=25+3a
ax+12=25+3a
ax-3a=25-12
a(x-3)=13
If Paul mows the lawn once, he earns 1*25.50. If he mows it twice, he earns 2*25.50, and so on. So, he earns L*25.50. But, he spends 3.50. So the equation is: