35% of the revenue produced at the auction will go to charity. The morning participants spent an average of $50 each. The afternoon attendees spent an average of $75 each. Write an algebraic expression. Use m for morning participants and a for afternoon participants.

Let m be the number of participants in the morning.
Let a be the number of participants in the afternoon.

The amount spent in the morning:
$50 × m = $50m

The amount spent in the afternoon:
$75 × a = $75a

Total revenue produce at auction:
= Total spending in morning and afternoon
= $50m + $75a

Amount going to charity:
= Total spending × 35%
= Total spending × 0.35
{Remember to put brackets around Total spending since ($50m + $75a) is one group in this calculation}
= ($50m + $75a) × 0.35
= ($50m × 0.35) + ($75a × 0.35)
= $17.5m + $26.25a

Hope this helps! :)