Aknife is twice the cost of a spoon. 8 spoons and 12 knives cost £46.08. work out the cost of 1 knife.

A knife costs £2.88.

Step-by-step explanation:

Create two equations using what you know to show the problem.

k = 2s

12k + 8s = 46.08

Substitute the first equation in for k, then isolate s to find how much spoons cost.

12(2s) + 8s = 46.08

24s + 8s = 46.08

32s = 46.08

s = 1.44

A spoon costs £1.44. To find the price of a knife, double the cost of a spoon:

1.44 * 2 = 2.88

A knife costs £2.88.

answer: 15

step-by-step explanation:

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places