A man weighs 100 kilograms plus half its own mass. What is his total mass?

Guest Apr 19, 2015

#2**+5 **

$${\mathtt{M}} = {\mathtt{100}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}}$$

$${\mathtt{M}}{\mathtt{\,-\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\frac{{\mathtt{2}}{M}}{{\mathtt{2}}}}{\mathtt{\,-\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\mathtt{M}} = {\mathtt{200}}$$

gibsonj338
Apr 19, 2015

#1**+5 **

Let M be the mass. Then

M = 100 + M/2

Subtract M/2 from both sides

M/2 = 100

Multiply both sides by 2

M = 200 kg (Heavy man!)

.

Alan
Apr 19, 2015

#2**+5 **

Best Answer

$${\mathtt{M}} = {\mathtt{100}}{\mathtt{\,\small\textbf+\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}}$$

$${\mathtt{M}}{\mathtt{\,-\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\frac{{\mathtt{2}}{M}}{{\mathtt{2}}}}{\mathtt{\,-\,}}{\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\frac{{\mathtt{M}}}{{\mathtt{2}}}} = {\mathtt{100}}$$

$${\mathtt{M}} = {\mathtt{200}}$$

gibsonj338
Apr 19, 2015