Jake made a total of 7 copies at a copy shop, with some being black-and-white copies and some being color copies. Black-and-whit
e copies cost 8 cents, and color copies cost 15 cents. If Jake spent a total of 70 cents on copies, which system of equations can be used to determine the number of black-and-white copies and the number of color copies he made? Assume b is the number of black-and-white copies and c is the number of color copies.
Jake spent a total of 70 cents. b = black-and-white = 8 cents c = color = 15 cents
70 = 8b + 15c
he made a total of 7 copies b + c = 7
system of equation: 70 = 8b + 15c b + c = 7
--------------------------
b + c = 7 b + c (-c) = 7 (-c) b = 7 - c
plug in 7 - c for b
70 = 8(7 - c) + 15c Distribute the 8 to both 7 and - c (distributive property)
70 = 56 - 8c + 15c Simplify like terms
70 = 56 - 8c + 15c 70 = 56 + 7c
Isolate the c, do the opposite of PEMDAS: Subtract 56 from both sides
70 (-56) = 56 (-56) + 7c 14 = 7c
divide 7 from both sides to isolate the c
14 = 7c 14/7 = 7c/7 c = 14/7 c = 2
c = 2 ---------------
Now that you know what c equals (c = 2), plug in 2 for c in one of the equations. b + c = 7 c = 2 <em>b + (2) = 7 </em><em />Find b by isolating it. subtract 2 from both sides b + 2 = 7 b + 2 (-2) = 7 (-2) b = 7 - 2 b = 5
Jake made 5 black-and-white copies, and 2 color copies hope this helps
Beth earns $54 per day and $10 for each extra hour she works. Ray earns $60 per day and $8 for each extra hour he puts in. They both work five days a week. The equations show their weekly earnings with respect to how many extra hours they work.
