A sequence increases by 5 each time and the first term is x. The sum of the first four terms is 54. Set up and solve an equation to work out the value of x.

The first term is x, and if it increases by 5 each time then the second term is x+5, third is x+10, and the fourth is x+15.

Adding these values together we get 4x+5+10+15, and this equals 54.

Therefore; 4x+30=54.

Take 30 from both sides; 4x=24

Divide both sides by 4; x=6