MAKE AN EQUATION, solve it.
A man has $0.70 in dimes and nickels. He has 8 coins altogether. How many nickels does he have?

Number of nickels: 2,

Number of dimes: 6

Step-by-step explanation:

Say d ⇒ number of dimes, n ⇒ number of nickels; from this we can formulate two equation knowing the cost per dime ⇒ $ 0.1, and the cost per nickel ⇒ $0.05

d + n = 8,

0.1 * d + 0.05 * n = 0.7 ⇒ Let us solve through substitution

d = 8 - n into 0.1 * d + 0.05 * n = 0.7,

0.1 * ( 8 - n ) + 0.05 * n = 0.7,

0.8 - 0.1 * n + 0.05 * n = 0.7,

0.8 - 0.1n + 0.05n = 0.7,

- 0.05n = - 0.1,

Number of nickels: 2 ⇒ Now let us substitute this value into the first equation as to solve for d, dimes

d = 8 - 2,

Number of dimes: 6

you can't solve x because it is 2 linear equation and you only have one equation

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!