Hiya. I'm going to rewrite the second equation.
By subtracting 5x by both sides, I'll be able to have y by itself:
-y=-5x+13
I'm going to then divide both sides by -1 to get:
y=5x-13.
Then, I'm going to plug that equation into the first equation
3x+2(5x-13)=39
Factor:
3x+10x-26=39
Combine like terms:
13x=65
Divide both sides by 13 to get x by itself to get x=5
Plug this back into the equation of y=5x-13
y=5(5)-13 to get y=12
A the 12 pack box of 1.4 ounce bars
You have to find the unit rate
SO..
7.70 / 154 = 0.05
So it cost her 0.05 cents for each text.
So then you divide $ 5.25 by the unit rate to get the number of text
5.25 /0.05 = 105
so she sent 105 text
To check it you just multiply the unit rate by the number of text you got and you show come up with $ 5.25
0.05 x 105 = 5.25
