Daniel got 86% on his test and he solved 5 points extra credit problem. What would be his new grade on this test?
1 answer:
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You have the equations set up correctly. I will use r and b as the variables to make it easier to follow.
12r + 8b = 70
20r + 12b = 110
First let's solve one of the equations for one of the variables.
12r = 70 - 8b
Now plug that in for r in the second equation.
Simplify
b = 5 grams
Now plug 5 in for b in one of the original equations to find r.
12r + 8(5) = 70
12r = 30
r = 2.5 grams
So the red marbles weigh 2.5 grams, and the blue marbles weigh 5 grams.
12r + 8b = 70
20r + 12b = 110
First let's solve one of the equations for one of the variables.
12r = 70 - 8b
Now plug that in for r in the second equation.
Simplify
b = 5 grams
Now plug 5 in for b in one of the original equations to find r.
12r + 8(5) = 70
12r = 30
r = 2.5 grams
So the red marbles weigh 2.5 grams, and the blue marbles weigh 5 grams.
