6c=18 how do you solve this equation

One card is dealt from a 52 card deck. find the probability that the dealt card is a 4 or a black 7

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?

Use the balanced scale to find the conversion factor that can be used to convert the number of blocks to the weight of the blocks in pounds.