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For a rectangle of 12cm in length, 8cm in width. Calculate rectangular perimeter

A survey showed that of 120 secondary school students: 52 of them have a dog, 31 of them have a cat and 19 of them have both.
How many of the 120 students have neither a dog nor a cat?
Answer: ........ students.

75+20+45+55+80=?

75+34+43+25+66=?

75+34+43+25+66+57=?

75+12+43+25+88+50+57=?

Given two positive real numbers x,y so that $x + y \geq 10$

Find the smallest value of P , know P = $2 x + y + \frac{30}{x} + \frac{5}{y}$

A survey showed that of 120 secondary school students: 52 of them have a dog, 31 of them have a cat and 19 of them have both.
How many of the 120 students have neither a dog nor a cat?
Answer: ........ students.

Compare:

2^30 and 3^20

Violet x:

15+10+30+70+10+90+85

Compare: 99^20 and 9999^10