Please help me with steps to work out the following problem. Simplist way possible.

Question

Mary needed different coloured balloons for decoration. She had $1.25 (Australian dollars) and spent it all on a number of white, red, and blue balloons. A white balloon costs $.10, a red one $.15 and a blue one $.05. She bought one white balloon less than the red and the total number of white and red balloons equals the number of blue ones. How many of each colour doc Mary buy?

Thank you :)

Answer 1

let number of reds be x
number of whites = x-1
number of blues = x + x-1 = 2x - 1

now to the value of these:

.15x + .10(x-1) + .05(2x-1) = 125
times 100
15x + 10(x-1) + 5(2x-1) = 12500

solve for x, and sub back in my definitions