Quick Maths

In 150 students, 90 take Maths, 80 Biology, 70 Chemistry; 40 take both M & B, 30 M & C, 25 B & C and 15 all three. How many take at least one subject?

Compute \(\frac{64{,}000{,}000\times0.004}{0.0001}\) in standard form.

From \(x+4y=9\) and \(2x+8y=18\), find \(x+2y\).

Express \(\frac{9}{28} - \frac{2}{7}\), correct to two significant figures.

In a survey of 120 consumers, 70 prefer coffee, 55 prefer tea and 30 prefer both. How many prefer coffee only?

Solve for \(x:y\) given \(\dfrac{3x-y}{4}=\dfrac{x+2y}{7}\).

If \(A = \frac{1}{2}b(a + b)\), make \(a\) the subject of the relation.

If \(21_{x} = 111_{2}\), find the value of \(x\).