Answer: 630 straws were in the box before any was used.
Step-by-step explanation:
So we know that 15% were used out of the remaining straws after 30 was used.
So if 630 straws were there in total then we will substrate 30 from the total 630 and multiply the rest by 15% to find out if it equals 90.
630 - 30=600
600 * 15%=?
600 * 0.15=90
So it makes sense that 630 straws were there in total.