Equation

3/t + 4/5 = 5 + 5/7t  common denominator is 35t. Multiple both sides by 35t.

35t(3/t + 4/5) = 35t(5 + 5/7t)
105 + 28t = 175t + 25
105 - 25 = 175t - 28t
80 = 147t
t = 80/147

return