Expanded notation for 67.734

The first digit, 6, is the tens. This is equal to 60.
The second digit, 7, is the ones. This is equal to 7.
The third digit, 7, is the tenths. This is equal to .7, or 7 tenths.
The fourth digit, 3, is the hundredths. This is equal to .03 or 3 hundredths.
The fifth digit, 4, is the thousandths. This is equal to .004 or 4 thousandths.

(2 × 4) + 7 = X

So to simplify, you just need to do everything in the brackets then add 7 to find the final value of X.

2 × 4 = 8

Put 8 back into the first equation

8 + 7 = X

X = 15