What expression is equal to 20+30

I’m stuck on this i don’t understand.

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

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.