Answer:
D. 192
Step-by-step explanation:
This problem involves a few steps. First, you need to determine how many eighth graders you have given that 112 represent 70% of the total number of eighth graders. You can solve this using a proportion:
Cross-multiply and divide: 70x = 11200 or 70x/70 = 11200/70 or x = 160
Since there are 160 total eighth graders and this is 
of the amount of seventh graders, we can set up an equation to solve for the total amount of seventh graders:
160 = x
Multiply by the reciprocal of your fraction on both sides:
x 160 = x ()
Solve for x: x = 192 seventh graders
Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
Answer:
A
Step-by-step explanation:
It is given that
a+b=20 -------------------- (1)
b+c=30 -----------------------(2)
We have to calculate
3 a + 4 b +7 c
Now multiplying equation(1 )by 3,we get
3 a+ 3 b=60 ----------------------------------(3)
and Multiplying equation( 2) by 4,we get
4 b + 4 c=120 -----------------------------------(4)
Adding expression (3) and (4),we get i.e left hand side of 3 to left hand side of 4 and right hand side of 3 to right hand side of 4.
3 a+ 3 b+ 4 b+ 4 c=60+120
Adding like terms, we get
3 a+ 7 b+ 4 c =180, Which is the required solution.
