Answer:
She will receive 70 advertisements
Explanation:
With the information of 7 ads per 10 emails, the ratio is 7/10 emails being ads
If there is 100 emails, then both numbers will be multiplied by 10
7*10 = 70
10*10 = 100
The ratio is now 70/100
This means she will receive 70 advertisements per 100 emails