Answer:
rectangle: 30 in^2
triangle: 12 in^2
composite: 42 in^2
Step-by-step explanation:
area of a rectangle: length times width
area of a triangle: 
composite area: break the area up by shapes you can find the area of, then add it back together
(x-3)(x+4). -3,4 multiply to -12, and add to get 1
1 is A - just plug and chug
2 is B - for 2 linear equations to have infinite solutions they mustbe the same
3 is C
4 is C - that is where they intersect
5 is A - same slope and different intercepts means no solutions
30% converted to a decimal is 0.30
310 x 0.3 = 93 students play an instrument
B. 6x^2+39x^2+54x is the correct answer.