10/12.86 = 0.7776

10/12.86 = ... (fraction or decimal)

£ 12.86 for 1 unit.

Divide both sides by 12.86

£ 1.00 for 1/ 12.86 = 0.07776

Multiply both sides by 10

£ 10.00 for 0.7776 units.

The math is simple: 10 / 12.86.

Set up a proportion

x / 1 = 10 / 12.86

Solve for x by multiplying both sides by 1

1 * x / 1 = 1 * 10 / 12.86

x = 10 / 12.86

Note that nothing changed, but that's due to the fact that we're multiplying by 1. Nothing changes when you do that.

x = 10 / 12.86

x = 10 / (1286 / 100)

x = 10 * 100 / 1286

x = 1000 / 1286

x = 2 * 500 / (2 * 643)

x = 500 / 643