Since 1/8 of his books are mystery and he has three of them, you would multiply 3 by 8 to find his total number of books which is 24.
Answer:
a) add x , subtract 1 and divide by 4
The solution of given equation 
<u>Step-by-step explanation:</u>
Given equation 1+3 x = -x +4
<em> Add 'x' on both sides , we get</em>
1 + 3 x + x = - x + x +4
1 + 4 x = 4
<em> Subtract '1' on both sides , we get</em>
<em> 1+4 x -1 = 4 -1</em>
4 x = 3
<em> Dividing '4' on both sides, we get</em>


<u><em>Final answer</em></u>:-
<em>The solution of given equation </em>
<em></em>

The mistake is in Step 1. The solver should have also squared
when squaring the other side of the equation.
<h3>Correctly solving</h3>

Y=4x because 20/5 equals 4
1 to 4
150mm is the same as 15cm
15cm:60cm
both divisible by 15
1cm:4cm
1 to 4