Two circles stand above a rectangle. Multiply the number in both circles but outside the rectangle by the number in the rectangle alone, then subtract the number outside every figure.

Both circles, outside the rectangle: 7. Rectangle alone: 5. Outside every figure: 13. So $7\times 5-13=22$. −3 uses the centre 2 instead of 7, 48 adds the 13 instead of subtracting it, and 42 uses 11 (left circle and rectangle) instead of 7.