5 + 3r = 5r - 19

I need to solve for "r" and i can't think please help
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The difference between two numbers is one. three times the larger number minus two times the smaller number is 9. what are the two numbers

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?

Which radical expression is a rational number? a. √ 360 b. √ 644 c. √ 225 d. √ 122