Help me with this very confused

The sum of the product of 4 and x and the product of 7 and y is 61. the sum of the product of 12 and x and the product of 21 and y is 61. what are the values of x and y?

The areas of two similar triangles are 72dm2 and 50dm2. the sum of their perimeters is 226dm. what is the perimeter of each of these triangles?

An object is accelerating at a constant rate. its velocity in feet per second as a function of time in seconds can be modeled by the linear function v(t) = 2.5t. what does the dependent variable represent for this function? a) acceleration b) distance c) slope d) velocity