Five times the sum of 3 and twice some number is 70. What is the number ?

1st attempt

3 + 5x + 2x = 70

7x = 70- 3

7x = 67

x = 67 / 7

2nd attempt

5 ( x+ 3+2x ) = 70

5x + 15 + 10x = 70

15x = 70 - 15

15x = 55

x = 55 / 15 but the book answer 11/2

where did i screw up ?