Translation of "Sumó" in English

Su profesor, lejos de excluirlo, lo sumó,

had a teacher who, instead of excluding him, integrated him,

Recién se nos sumó un tercero: el auto de atrás.

We now have a third one: the car from behind.

(Al principio muy poca gente se sumó a este movimiento de protesta… pero, en cuestión

(At first very few people joined this protest movement ... but, in question

Pero un análisis reciente hecho por dos economistas sumó todos los impuestos a la renta.

But a recent analysis by two economists added up all the income taxes.