To solve this expression, we follow the order of operations (PEMDAS/BODMAS):

Perform the operation inside the parentheses:
45:9 = 5

Substitute the result back into the expression:
35•45 + (5-1)•980 - 780

Perform the subtraction inside the parentheses:
5 - 1 = 4

Substitute the result back into the expression:
35•45 + 4•980 - 780

Multiply the numbers in the next set of parenthesis:
4•980 = 3920

Substitute the result back into the expression:
35•45 + 3920 - 780

Multiply the remaining numbers:
35•45 = 1575

Subtract the final result:
1575 + 3920 - 780 = 4715

Therefore, 35•45 + (45:9-1) • 980 - 780 equals 4715.