To find the x-intercept, set y=0 and solve.
... 0 = log(12x +7) -3
... 3 = log(12x +7) . . . . add 3
... 1000 = 12x +7 . . . . take the antilog. (10^3 = 1000)
... 993 = 12x . . . . . . . .subtract 7
... 82.75 = x . . . . . . . . divide by 12
To find the y-intercept, set x=0 and solve.
... y = log(12·0 +7) -3
... y = log(7) -3 . . . . . . simplify
... y ≈ 0.85 -3 = -2.15 . . . . use a calculator for the log function