Jenny decided to grow out her hair. Over 6 months, her hair length grew by 100%. During the next 6 months, her hair length grew by 50%. What was the combined increase in hair length during the entire year

150% in 12 months ...

In your mind, you could think 100% more is 200% and 50% of that is another 100% so 200% increase. Let's see on paper. x will be her current hair length.

x + x +.5 (x + x)

x + x is simply her hair length doubling. This is when it grew 100% longer. Then, from that, we have 50% more, so we have to add 50% of the x + x.

2x +.5x +.5x

3x

Subtract our starting length.

3x - x = 2x

The difference is 2 hair lengths, or 200% her original length of hair.