4d + 12 = 4(d + 3)
Basically, you just need to determine what 4d and 12 have in common. In this case, they both divide evenly by 4. Therefore 4 (d + 3) = 4d + 12 according to the distributive property.
1+2=3.
30/3=10
10x1=10
10x2=20
So the answer would be £10:£20
And to check if it’s right £10 + £20= £30