Sandra's dog weighs 3 1/2 pounds. each dog he gains 2/3 of a pound. if he continues to gain this much weight each week, how much will he weigh in 8?

Multiply the weight gain per week by the number of weeks, then add it to the staring weight.

2/3 lb x 8 week = 16/3 = 5 1/3 pounds.

Since both fractions have different denominators, convert the weights to improper fractions, then turn them into fractions with a common denominator then simplify:

3 1/2 =7/2

5 1/3 = 16/3

Common denominator is 6:

7/2 * 3 = 21/6

16/3 x 2 = 32/6

Now add:

21/6 + 32/6 = 53/6

No convert back to proper fraction:

53/6 = 8 5/6 pounds.

step-by-step explanation:

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870