Answer:
Step-by-step explanation:
5x+9y=-3 Multiply both sides by 8
40x+72y=-24
-53x-8y=-3 Multiply both sides by 9
-477x -72y= -27
sum the equations vertically to eliminate one variable
40x+72y= -24
-477x-72y= -27 (the y cancels out )
-477x =-51 (-24 + -27=-51)
-477x=-51 / -477 divide both sides by -477
x =51/437
5x 51/437=9y= -3 substitute the value of x
y= -174 /437
(x,y) = (51/437, -174/437)
Answer:
C) 4
Step-by-step explanation:
-2(10)+-3(-6)
It would be -2
Let's assume there is n number of nickels coin and q number of quaters coin.
Given that there are 54 coins in total. So, sum of n and q must be equal to 54.
So, n + q =54.
Hence, q = 54 - n ...(1)
Now 1 nickel is worth of $0.01 nickel. So, n nickel will woth of 0.01n.
Similarly q quarters will worth of 0.25q.
Given that a parking meter contains nickels and quarters worth $7.70. So, sum of 0.01n and 0.25q will be equal to 7.70. Therefore,
0.01n + 0.25q = 7.70
From equation (1) we can plug in q=54-n in the above equation. So,
0.01n + 0.25 (54-n) = 7.70
0.01n + 13.5 -0.25n = 7.70
-0.24n + 13.5 = 7.70
-0.24n = 7.70 - 13.5
-0.24n = -5.8

So, n= 24.167
Hence, n= 24 ( rounded to nearest integer).
Next step is to plug in n=24 in equation (1). So,
q = 54 - 24 = 30.
Hence, there will be 24 nickel and 30 quarter.