The letter "x" is often used in algebra to mean a value that is not yet known. It is called a "variable" or sometimes an "unknown". In x + 2 = 7, x is a variable
25 would be your final answer.
Answer: 51?
Warning!:
I might be wrong because I haven't done this in a long time, so make sure to double-check.
Other than that, I hope this helps!
Let the number of blue marbles be x
number of yellow marbles = x/3
number of green = x- 90
ATQ
x + x/3 + x - 90 = 694
2x + x/3 = 784
(6x + x)/3 = 784
7x/3 = 784
x = 784 x 3/7
x = 112 x 3
x = 336
number of blue marbles = 336
Use any letter "x" is the usual one but since you have 2 you can use 2 different ones.
