By finding the differences between dependent values, you can determine the degree of the model for data given as ordered pairs. If the first difference is the same value, the model will be linear. If the second difference is the same value, the model will be quadratic.
Also you can solve it by plotting the dots. If the graph seems a straight line it is linear and quadratic if it is a parabola.
For the data set given it is a linear relation
Line of best fit: y=3.18x+54.92
For x=7;
y=3.18*7+54.92
y=77.18
