Simple math.
We she has a total off 100 colored counters
55 are reds
the rest are green or black
green are 4x than black
we can write it as,
100 = 55 + 4x + x
x will represent black while 4x will be black times 4 (or simply green).
Now time to compute.
move 55 to the left and change sign.
100 - 55 = 4x + x
Now add 4x and x and compute 100 - 55
we have,
45 = 5x
divide both 45 and 5x to 5.
(45 = 5x)/5
we have,
9 = x
therefore Sarah has a total of 9 black counters.
But your question is how many green counters she has?
So we need to multiply black counters to 4 to get it.
so we have,
9 * 4 = 36
so Sarah has a total of 36 green counters.
To check
we need to add all red, green and black counters. It should total to 100 colored counters.
55 + 36 + 9 = 100
55 + 45 = 100
100 ✔ 100
I hope it helps.
