Answer:
Jenna had 25 quarters and 15 dimes.
Step-by-step explanation:
Let Q = the number of quarters and D = the number of dimes.
Then:
1) Q+D = 40 "One week she had 40 coins, all of them dimes and quarters...."
2) 0.25Q+0.1D = $7.75 "...she had a total of $7.75."
Rewrite equation 1) as: D = 40-Q and substitute into equation 2).
2a) 0.25Q+0.1(40-Q) = 7.75 Simplify the left side.
2b) 0.25Q+4-0.1Q = $7.75 Subtract 4 from both sides.
2c) 0.25Q-0.1Q = 3.75 Combine the like-terms on the left side.
2d) 0.15Q = 7.75 Divide both sides by 0.15
2e) Q = 25 and:
D = 40-Q
D = 40-25
D = 15
Jenna had 25 quarters and 15 dimes.
9514 1404 393
Answer:
(3, 1)
Step-by-step explanation:
We assume you want the solution to the system ...
The second equation gives a nice expression for x, so we can use that in the first equation.
2(y+2) -3y = 3 . . . . substitute for x in the first equation
2y +4 -3y = 3 . . . . . eliminate parentheses
-y = -1 . . . . . . . . . . . collect terms, subtract 4
y = 1 . . . . . . . . . . . . multiply by -1
x = 1 +2 = 3 . . . . . . substitute for y in the second equation
The solution is (x, y) = (3, 1).
9514 1404 393
Answer:
$2.98
Step-by-step explanation:
The amount of interest earned is ...
I = P((1 +r)^t -1)
I = $9(1.1^3 -1) ≈ $2.98
Daniel will earn about $2.98 in interest in 3 years.
