Set A has 8 elements, set B has 12, and their union has 15. How many elements are in the intersection?

A recipe calls for 2 cups of flour for 12 cookies. How many cups for 30 cookies?

In a class of 30 students, 18 play soccer and 12 play basketball. If 5 play both, how many play neither?

If the universal set U has 50 elements, set A has 20, set B has 30, and A∩B has 10, what is |A' ∩ B'|?

A car travels at 60 mph for 2 hours, then at 40 mph for 3 hours. What is the total distance?

In a Venn diagram of two sets, the region outside both sets represents elements in:

A number is increased by 25% then decreased by 20%. The net change is:

If |A| = 15, |B| = 10, and |A∪B| = 20, what is |A∩B|?

A mixture of 10 liters contains 30% acid. How many liters of pure acid must be added to make 50% acid?

In a survey, 70 like cats, 50 like dogs, and 30 like both. If 120 are surveyed, how many like neither?

If a:b = 2:3 and b:c = 4:5, what is a:c?

What is the local name for a Mersenne prime of the form 2^p - 1?

What event happened in 1640 regarding Fermat's Little Theorem?

Which Mersenne prime exponent p is known to produce a prime but is not prime itself?

What is the smallest Fermat number that is not prime?