Lightning starts a forest fire at a point with map coordinates (23, 25) . Lundi has coordinates(15,19) and Winsor has coordinates(23,17). Each unit on the map is 1 km. Which town(Lundi or Winsor) is at greater risk from the fire?

so, converting firstly the mixed fractions to improper fractions and then "adding".

a_n = a_1 + (n - 1)d

the first term is 6.

the common difference d = ?

when you find d, replace n with 7 and d with the common difference to find your answer.