The solution cannot be x=45 and y=44
Your first formula is x+y=90, and 45+44 < 90.
Solve your first formula for y. (y=90-x)
Plug in the 90-x into your second formula
2.15x+2.4(90-x)=202.35
Multiply 2.4 * (90-x)
2.15x+216-2.4x=202.35
Add 2.15x and -2.4x and subtract 216 from both sides
-.25x=202.35-216 (-13.65)
Solve for x
x=-13.65/-.25 = 54.6
Solve for y
y=90-54.6=35.4



--
John C


"K. Carter" wrote:

I need help building a formula to calculate both the "x" and "y" values for
the following equation:

x + y = 90
2.15x + 2.4y = 202.35

The solution would be x = 45 and y = 44, but I haven't found a formula that
work yet!