Question

18-16y=-312
78x-16y=408

A: elimination, (-); (12,-33)
B: Substitution (12,33)
C:Substitution (12,-33)
D: Elimination (-) (12,33)

Answer 1

hmm...is the 1st eqn 18-16y=-312 or 18x -16y=-312?

Answer 2

18x

Answer 3

:P hahahaa im anticipating UR typos lol

so what happens when u add the two eqns together?

Answer 4

96x-32y=96

Answer 5

Oooo sorry my mistake - should be subtracting one from the other...sorry!

Answer 6

-60x=-720

Answer 7

then i divide

Answer 8

which is 12

Answer 9

:) see what i meant by u no needing any more help? lol

Answer 10

im confused on what next

Answer 11

cuz' u solve it by ELIMINATING y at first, it is by..... ;)

Answer 12

33?

Answer 13

18x - 16y = -312
78x - 16y = 408 --->(-1)
--------------
18x - 16y = -312
-78x + 16y = -408 (result of multiplying by -1)
--------------add
-60x = - 720
x = -720/-60
x = 12
now sub 12 in for x in either of the equations to find y
18x - 16y = -312
18(12) - 16y = -312
216 - 16y = -312
-16y = -312 - 216
-16y = -528
y = -528/-16
y = 33

elimination (12,33)

Answer 14

next is put x=12 back into either one eqn to solve for y...nevermind u figured it out on ur own already :)

Answer 15

thank u, kelliegirl - i was just trying not to give out the solution myself :) but ur proof is good!

Answer 16

I should not have interrupted your explaining...you were doing good..sorry about that superdave