Answer:
9.7%
Explanation:
Last week the 100% cost was $31
Now it's $34, we just have to find that % cost first. A ratio is in hand
100%. x
--------. = ----------
$31. $34
Cross multiplying we get
(34)(100) = 31x
31x = 3400
Dividing both sides by 31
x = 3400/31
x = 109.7%
Now that we see that it was raised to 109.7, we can subtract this from 100% to get
9.7% increase