standard_description: Write, read, and evaluate expressions in which letters stand for numbers.
problem_activity: Evaluate the expressions.
a.
$$24\div(2+1)+(11-8)\times2$$
b.
$$3^2\times4-10+(12-3)^2$$
c.
$$(3\times4)^2-10\times(12-3^2)$$


aligns: no