Either 7x or -3x hope this helps hun!!
Answer:
16
Step-by-step explanation:
To solve, we can use an equation finding the average of the siblings'ages.

I think you would distribute what is in the parentheses and then make it so only a and b are on the left and i and the other characters that can be simplified are on the left but feel free to Google it.
Twice means times 2.
1) 2(ab) gives twice the product of a and b.
2) (2a)b gives the product of twice a and b.
Answer:
The range is 40.
Step-by-step explanation:
Range is just the largest number minus the smallest.
70 - 30 = 40