$(7.5 \times 7.5 + 37.5 + 2.5 \times 2.5)$ is equal to

What value will come in place of the question mark (?) in the following question? (You are not expected to calculate the exact value)
$21 + 39 \times 2.9 + 8.99 = ?$

What approximate value will come in place of the question mark $(?)$ in the given equation? (You are not expected to calculate the exact value)
$\frac{1810}{24.05} \times 7.95 + 11.02 \times 18.88 = ? - 306$

Eight persons are planning to share equally the rent of a car. If one person withdraws from the arrangement and the others share equally the entire cost of the car,then the share of each of the remaining persons increases by what fraction?

If $(x+\frac{1}{x})^{2}=3$,then the value of $(x^{72}+x^{66}+x^{54}+x^{36}+x^{24}+x^{6}+1)$ is

What will come in place of the question mark (?) in the following expression?
$(4444 \div 40) + (645 \div 25) + (3991 \div 26) = (?)$