There are two ways to do this problem:
First way:
Two workers earn £300 between them.
One worker earns £x
The other earns £300-£x
One worker gets £25 more than the other.
So £x = £300-£x + £25
x = 300 - x + 25
x = 325 - x
2x = 325
x = 162.50
One worker earns £x = £162.50
The other earns £300-£x = £300-£162.50 = £137.50
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Second way:
One worker gets £25 more than the other
Other worker gets £x
So the one worker gets £x + £25
Two workers earn £300 between them.
Therefore the equation is
£x + £x + £25 = £300
x + x + 25 = 300
2x + 25 = 300
2x = 275
x = 137.50
So
The other worker gets £x = £137.50
The one worker gets £x + £25 = £137.50 + £25 = £162.50
Edwin