13.1 + (19.32 - 8) = ? I know the answer is 24.42 but it says the answer has to be to the correct number of significant figures. so would that make it 24.5 or have I got that wrong

When adding or subtracting numbers, the correct number of s.f. is dictated by the numbers to the right of the decimal. The smallest number to the right wins. 13.1 is ok to the tenth, 19.32 to the hundredths, and 8 to the whole number. Therefore, the 24.42 must be rounded to 24 (because 8 has no numbers to the right of the decimal).