Answer:
boys = 9 ( eighth grade ) + 1 ( seventh grade) = 10 boys
girls = 3 (eight grade) + 9 ( seventh grade) = 12
probability = 22÷ 2
= 1/11
Answer:
a=3, c=-4, x=8
Step-by-step explanation:
5=4a-7
4a-7=5
4a=5+7
=12
a=12÷4
=3
3-8c=35
-8c=35-3
=32
c=-32÷8
=-4
-1/2x-7=-11
-1/2x=-11+7
=-4
x=4÷1/2
=4/1×2/1
=8
C) (0.85 + x/100)(250+145) does not give the correct answer.
Explanation
A) works; adding the two costs together is 250+145=395. We multiply this by 0.85 because 100%-15%=85%=0.85. We also have x% tax, which is represented by x/100, added to 100% of the value, or 1.00. Altogether this gives us
395(0.85)(1+x/100) = 395(0.85 + (0.85x/100)) = 395(0.85) + 395(0.85x/100)
= 395(0.85) + 395(0.0085x)
B) works; we have 250+145 for the original price; we have 85% = 0.85 of the value; we also have 100% + x%, which is (100+x)/100.
C) does not work; (0.85+x/100)(395) does not take into consideration that you are finding the tax after taking the 85%. This will simplify out to
0.85*395 + (x/100)(395) = 335.75 + 395x/100 = 335.75 + 3.95x, which is too much.
D) works; simplifying the expression from A, we have 395(0.85) + 395(0.0085x) = 335.75 + 3.3575x.
