Question

solve the system using any algebraic method
0.25x+0.5y=7.5
0.4x+0.5y=9
Show work for a medal :)

Answer 1

Use elimination
Multiply everything by 100, that will get rid of the decimals :)
Multiply top equation by -1
Add equations to eliminate y

-25x -50y = -750
40x +50y = 900
----------------
15x + 0 = 150
15x = 150
x = 10

Answer 2

so whats y

Answer 3

take the top equation and put it in terms of y:

.5y = 7.5 - .25x
y = 15 - .5x

plug into second equation and solve for x

0.4x + 0.5(15 - .5x) = 9

0.4x + 7.5 - .25x = 9
0.15x = 1.5
x = 10

plug x into any equation to find y:

.5y = 7.5 - .25(10)

y = 15 - 2.5 = 12.5

Answer 4

i figured you could figure that out
substitute x=10 into one of original equations

Answer 5

y is not 12.5
what do you think?

Answer 6

x=10 and y=10

Answer 7

alright
40x + 50y = 900
x = 10
400 + 50y = 900
50y = 500
y = 10

Answer 8

y = 15 - .5(10)
y = 15 - 5
y = 10