Each of the members must raise at least $69.46.
To start they need to raise $552.50. However, they have already raised 12% of it. They only need to raise 88% of it.
552.50 x 0.88 = 486.2
Divide the remaining amount by 7 to determine how much each individual must raise.
486.2 / 7 = 69.46
M is -0.7 because -1.4 divided by two gives -0.7
X + 3 * 21 = 12
x + 63 = 12
x = 12-63
x = -51
The wording was a little odd, but I hope this is what you’re looking for!