There is a two-digit number whose units digit is six less than the tens digit. four times the tens digit plus five times the units digit equal 51. find the digits.

T = U + 6
4T + 5U = 51 substitute for T
4(U + 6) + 5U = 51
4U + 24  + 5U = 51
9U + 24 = 51
9U = 27
U = 3

t = U + 6
t = 3 + 6
t = 9

Check
4*t + 5*u = ? 51
4*9 + 5*3 = ? 51
36 + 15 =? 51
51 = 51 It checks.

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