Word problems w/ elimination/substitution

Question

the units digit is 8 times the tens digit of a two-digit number. The original number minus the number formed when the digits are reversed is -63. What’s the original number?

a company invests in 2 accounts. An account that provides more cash flow freedoms pays 2.2% annual interest and the other pays 7.5% annual interest. If the company invests $5000 less in the 2.2% account than in the other account and makes $2218 total interest income in a year, how much is invested at each rate?

Answer 1

I'll do the first one.

u = 8t

10t + u - (10u + t) = -63

10t + u - 10u - t = -63

9t - 9u = -63

t - u = -7

t - 8t = -7

-7t = -7

t = 1

u = 8(1)

u = 8

18