Eight goes into 45, 5 times so it would be 5 and 5/8.
It would be
3.5 × 10⁻³ kg.
The decimal point must be moved 3 places to the right in order to have it behind the first non-zero digit; this gives us the exponent of 3, and since we are moving the decimal to the right, it is a negative exponent.
Start with

Add 2x to both sides:

Subtract 21 from both sides:

Divide both sides by 5. Since it is positive, we don't have to change the inequality sign:

So, the answer is 
I believe its 31/100! <span>To write 0.3111 as a fraction you have to write 0.3111 as numerator and put 1 as the denominator. Now you multiply numerator and denominator by 10 as long as you get in numerator the whole number.</span>