Make the denominators all the same.
LCM (4;2) = 4

Multiply both fractions for 4 to delete denominators
1+3x = 10
Move know terms to the right with changed sign
3x = 10-1
3x = 9
Since the x is multiplied for 3, divide both terms for 3
3x/3 = 9/3
x = 3