Answer:

Step-by-step explanation:
Let
y --->Mala's age
x---> sister's age
we know that
---> equation A
so
The sum of ages of the sisters is

substitute equation A in the expression of the sum of ages

simplify

Answer:
75 quarters 25 nickels
Step-by-step explanation:
q=quarters n=nickels
q+n=100 n=100-q
0.25q +0.05(100-q)=20
From now I will multiply by 100 to avoid decimals
25q + 5(100-q)=2000
20q=1500
q=75 n=25
75*0.25= 18.75
25*0.05=1.25
18.75+1.25=20
A of trapezium = ((a+b)/2)(h)
A = ((10+10+4)/2)(8)
A = (24/2)(8)
A = 12(8)
A = 94
The area is 94ft²
15. 
Step 1: Distribute the subtraction sign to all the numbers in the second set of parentheses...


Step 2: Combine like terms (
's go with
's)




Step 3: Combine like terms (
's go with
's)




Step 4: Combine like terms (normal numbers go with normal numbers)

1 + 2
3

You were correct!
16. 
I don't really know how to explain this one but I got: (7m-6n)(7m-6n)