Answer:
(a) 56
Explanation:
You want the number that is 80% of 70.
Percent
In this context, "of" means "times." Thus "80% of 70" is "80% times 70".
Some calculators have a % key that lets you calculate this directly. Otherwise you may need to convert the percentage to a fraction.
The % symbol is effectively interchangeable with "/100", so we have ...
80% of 70 = 80/100 × 70
At this point, you can employ what you know about multiplication and division to simplify this to a problem you can do in your head.
= (80×70)/100 = (8×7×100)/100 = 8×7 = 56
If you want a grade of 80%, you need to get 56 questions correct.