The costs of 5 similar digital cameras and 3 similar video cameras is $3,213. Each video camera costs 4 times as much as each digital camera. John buys a digital camera and a video camera. How much does he pay?

Let,

digital cameras be "x"

video cameras be "y"

Now,

According to the question,

5x + 3y = $3,213 ... equation (1)

y = 4x ... equation (2)

Taking equation (1)

5x + 3y = $3,213

Substituting the value of "y" from equation (2), we get,

5x + 3 (4x) = $3,213

5x + 12x = $3,213

17x = $3,213

x = $3,213 / 17

x = $189

Taking equation (2)

y = 4x

Substituting the value of "x", we get,

y = 4 ($189)

y = $756

Now,

John buys a digital and a video camera. So, it costs him ($189 + $756) = $945