égal or égale

Bonjour Catherine,

That's a very good question! The reason for 'égale' over 'égalent' is that the "phrase" or the calculation (being, a sum, a multiplication etc.) is considered as one item. Therefore, the singular form "égale" is preferred. Sometimes you might find the plural form "égalent" but it is not what L'Académie française recommends. 

I hope this is helpful.

Bonne journée !