Nathan B. answered 02/14/20
Elementary and Algebraic skilled
Here's what we know:
9c + 7t = 72 (9 chairs and 7 tables cost $72)
3c + 5t = 42 (3 chairs and 5 tables cost $42)
Let's use the elimination method. Multiply the latter equation by -3 so we can subtract it from the former:
9c + 7t = 72
-9c - 15t = -126
-------------------------
-8t = -54
Divide both sides by -8:
t = 6.75
Now to find chairs:
3c + 5 * 6.75 = 42
3c + 33.75 = 42
Subtract 33.75:
3c = 8.25
Divide by 3:
c = 2.75
Check -- place the values into the first equation:
9 * 2.75 + 7 * 6.75 = 72
24.75 + 47.25 = 72
72 = 72